In uk.d-i-y, Dave Plowman wrote:

If they are there to 'see' the switch in the dark, it's normal to have them
on with the light off, and off with it on. If it's a normal lighting
circuit, it sounds like he might have wired one side to earth, given that
there's not normally a neutral at a switch.

With incandescents, there's no need to wire the cold end of the neon
to earth: the neon goes across the switch contacts, and the cold resistance
of the blub forms an effective path to neutral (being massively lower than
the 'internal resistance' of a neon indicator). With the switch on, there's
no potential across the neon, so it goes out. A downside of this Ingeneous
scheme is that if the bulb blows, the indicator no longer lights; and it's
shot to pot if you use compact-flourescent or similar.

As for the cooker switch, it sounds as you say very much as if the wiring
to the 'Feed' and 'Load' sides of the switch have been swapped round.

Cheers, Stefek